Apparatus for the manufacture of lead oxide



July 16, 1940. D. DOYEN 2,208,146

APPARATUS FOR THE MANUFACTURE OF LEAD OXI DE Original Filed March 20, 1955 4 Sheets-Sheet l Zwrv eniow; QDanLeZ Dayan July 16, 1940. D. DOYEN 2,208,146

APPARATUS FOR THE MANUFACTURE OF LEAD OXIDE Original Filed March 20, 1935 4 Sheets-Sheet 2 H w WM Ea ng e 7 25672 July 16, 1940. D. DOYEN APPARATUS FOR THE MANUFACTURE OF LEAD OXIDE Original Filed March 20, 1935 4 Sheets-Sheet 5 Z /we'n Z 07; pan/1L8 L y 77/ /gifo n i7.

July 1 1940- D. DOYEN APPARATUS FOR THE MANUFACTURE OF LEAD OXIDE 4 sheets-sheet 4 W a W p w W.

. w m n K wm a l Tv w \w N "7 v at Wm R m \m I r! 5 Q W I u flu 4| w I 1 1 N 1 I l1 1 I um 1 fl M w F w m 2 MN Patented July 16, 1940 UNITED STATES APPARATUS FOR THE MANUFACTURE OF LEAD OXIDE Daniel Doyen, Brussels, Belgium, assignor to Prest-O-Lite Battery ration of Indiana Application March 20,

Company, 1110., a corpo- 1935, Serial No. 12,005.

Renewed November 13, 1939. In France Janu- 3 Claims.

This invention relates generally to an attrition mill, and more particularly to an apparatus for the continuous production of lead powder and lead oxides from lumps of metallic lead by attrition.

An object of the invention is the provision of a reliable and efficient apparatus of this character which is designed for automatic removal from the apparatus of the desired fine product, uncontaminated with coarse material.

Another object of the invention is to provide simple and efiective means which are so designed and constructed as to retain within the apparatus all coarse material until it is completely reduced to the desired powdered state.

A further object of the invention is the provision of positive and efficient means for the immediate return to the zone of attrition of coarse particles which have been refused passage by the separating means.

A still further object of the invention is to provide an apparatus of this character which is simple, inexpensive and rugged in construction and which is not liable to get out of order.

Other features of the invention reside in the construction and arrangement of parts herein-V after described, and particularly pointed out in the appended claims.

In the accompanying drawings wherein I have illustrated one form of the invention,-

Figure 1 is a side elevation of my lead oxide mill.

Figure 2 is a top plan view of the same.

Figure 3 is an end view of the apparatus looking toward th e feed end.

Figure 4 is an enlarged central longitudinal section taken substantially on line 4-4 of Figure 2.

Figure 5 is an enlarged transverse section taken on the line 5-5 of Figure 4.

Figure 6 is an enlarged fragmentary view of the annular rings.

Similar characters of reference indicate corresponding parts throughout the several views.

, While my invention may be employed for producing different kinds of finely divided materials, it has been primarily designed for producing by attrition lead powder and lead oxides from lumps of metallic lead. To this end the apparatus consists generally of a stationary enclosure or housing connected through ducts with a dust-separating means. Revolvable within the enclosure is a hollow member, preferably cylindrical in shape. which carries the working parts of the apparatus, such working parts comprising essentially, means for continuously introducing into said cylinder during rotation pieces of material divisible by attrition, separating means associated with the cylinder for removing from the zone of attrition the fine particles of disintegrated material, and

conveying means for returning 'to the zone of attrition particles which are too large to pass said separating means. There may also be included means for supplying an oxidizing agent to the cylinder in order that oxidization may be effected simultaneously with pulverization.

Referring now to the drawings, It indicates a suitable base and mounted thereon is a stationary housing H, having a center section 12 and end sections l3. Extending from the top of each end section I 3 is a duct l4, leading to dust-separating means I5, connected through piping 16 to a suction pump ll, driven by a motor I 8. Revolvable within the stationary enclosure H is a horizontal cylinder or drum l9, having "end plates 2D20a suitably secured to trunnions Zl-Zla, journalled in bearings 2222a, mounted on the base I0. Trunnion 2| is hollow and communicates at its outer end with feed hopper 23. Its inner end registers with a tube or pipe 24 which extends along the longitudinal axis of member l9 and which is provided with a screwconveyor 25 having a centrally disposed opening 26 therein, and with a central opening 25a through which the material is discharged into the drum. Each end section of drum I9 is in the form of a seriesof annular rings 21, separated from one another by spacing washers or collars 28 securely fastened to said drum and end plates by bolts 29. The spaces between rings 21 'constitute in effect endless slits 30 of desired width to permit disintegrated material of sufficient fineness to escape from the zone of attrition to a cylindrical chamber 3|, one of which is provided at each end of the drum. Theclogging of the endless slits 30 is eliminated by the construction shown in Figure 6. The thickness of each ring at its inner periphery is materially greater than its thickness at a point a short distance outward from the inner periphery, to provide cavities 32 between the rings of greater width than slits 30. Chambers 3| are formed by cylindrical screens 33, one of which is mounted at each endof drum IS in spaced relationship thereto. The interstices of screens 33 are smaller than the slots 30 and determine the degree of fineness of the finished product. Positioned below each screen 33 is a hopper 34 for the reception of material which passes through the screens. To protect the screens 33 from injury due to the weight of the material passing over them, I provide each screen with a perforated cylinder 35, securely fastened at one end to the drum l9, and at the other end to one of said end plates by screws 36, which also serve to hold screens 33 in position.

Material too coarse to pass through the screens is returned to the drum by means of special conveyors 31, mounted on partitions 38, one of which is located adjacent each end plate. As shownin Figure 4, viewed in conjunction with Figure 5, each conveyor 31 and partition 38 is associated with one of the drum endplates to form spiral passageways communicating at one end with one of said chambers 3| and at the other end with feeding tube 24.

The operation of my invention is as follows:

Pieces of metallic lead are placed in hopper 23 from which they pass through trunnion 2| to screw conveyor 25, which discharges them through opening 2511 into the central or trituratingzone of drum l9. As the latter revolves pieces of lead are carried for a short distance up the inner wall of the drum from which position they cascade to the bottom of the drum. The friction of the lead pieces causes the temperature inside the drum to rise. Air drawn through the drum by fan I! will oxidize the surfaces of said lead masses to lead suboxide, or litharge, or both, depending upon the temperature of the mill, and the quantity of air available. The oxide thus formed is abraded off and is discharged from the drum through slits 30. It will be noted that the direction of movement of the material through the drum is from the central portion toward both end portions. the drum is caught by screens 33, which permit particles of suitable degree of fineness to pass therethrough into hoppers 34. The coarser particles are picked up by spiral conveyors 3?, which are in the nature of Archimedes screws, and returned to conveyor 25, which delivers them through opening 25a to the attrition zone of the drum. The air passing through is exhausted through ducts i l from which, for hygienic reasons, it passes through dust collector I5, which removes any entrained particles of lead. It is then discharged into the atmosphere.

In the manufacture of partially oxidized lead powder, the percentage oxidation in terms of lead monoxide may be varied at will by varying the temperature of the mill, its speed of revolution, the amount of lead in the mill, and the quantity of air fed to the mill. For example, I have found that a very satisfactory oxide for storage battery purposes may be made by using a mill 65 centimeters in diameter, having a charge of 400 kilogs. of lead lumps, rotating the mill at a speed of approximately forty-seven (47) revolutions per minute while supplying air thereto at the rate of 350 cubic feet per minute. The product obtained is a mixture oflead monoxide and lead suboxide, with some finely divided metallic lead.

The fineness of the product discharged from the mill is governed, in the first instance, by the size of the slits 3|, which is readily adjustable by using collars 28 of different thicknesses. Any material not of suitable degree of fineness which is discharged through said slits, is sorted by screens 33. The use of slits 3| of predetermined size prevents much of the congestion which would occuron screens 33 were such slits not provided.

The advantages of the invention are now apparent. It provides means for the efficient and automatic removal from the apparatus of the desired;.product, uncontaminated with coarse ma The material which escapes from terial. All coarse material is retained within the apparatus, thus obviating the necessity of a subsequent screening operation, and transportation of coarse material for re-introduction into the apparatus. Another advantage of the invention resides in the simplicity and inexpensivenes-s of theauxiliary equipment required in connection with the main system. A still further advantage of my invention is that it provides means for the immediate return to the zone of attrition of coarse particles which have been refused passage by the separating means. Accumulation of quantities of coarse material in such locations as to impair'the efficiency of operation of the separating means is entirely avoided by the new and novel means provided for its early return to the zone of attrition. There is no probability oi" premature discharge from the mill of the abraded particles, as is the case with a uniformly perforated mill. All of the material must travel from the central portion to an end portion of the mill, thus enhancing the uniformity of product for every given set of operating conditions.

Theabove description is for purposes of illustration only and is not to be construed as in any way limiting the scope of the invention. Many .mod ifications will occur to those skilled in the art. It is my intention that this patent shall cover all such modifications as come within the scope of the appended claims.

When desirable, due to the nature of the material being treated or the fineness of the mesh of the screens 33, vibrating or beating means may be used to keep the screens clear and prevent clogging thereof.

What I claim as new and desire to secure by Letters Patent of the United States is 1, An apparatus for use in the production of lead oxides and powder'of lead comprising a revoluble container composed of an inner shell providing a zone of attrition surrounded by an outer shell, the inner shell having an imperforate central portion and openings of controlled size in the end portions thereof emptying into the chamber formed by the outer shell for the purpose of limiting the size of particle which may escape from the zone of attrition, a mechanical separating means in the outer shell which again limits the size of particle which may issue from the revoluble container, and means for supplying an oxidizing agent to said zone of attrition in combination with conveying means at either end of and wholly within the revoluble container leading from the-chamber formed by the outer shell to a preferred location within the zone of attrition.

2. In a device of the class described, a rotating cylindrical chamber having peripheral outlet adjacent each end thereof and an imperforate horizontal portion intermediate said ends, and axially located means having an outlet located approximately above the center of the imperforate horizontal portion for continuously delivering material to beacted upon to the center of said imperforate horizontal portion whereby there will be a continuous flow of product from the center of said chamber toward each end thereof.

3. In a device of the class described, a rotating cylindrical chamber having peripheral outlets adjacent each end thereof and an imperforate hori zontal portion, intermediate said ends, axially located means having an outlet located approximately above the center of the imperforate horizontal portion for continuously deliveringlumps of a material to be subjected to oxidation and abrasion to said imperforate portion, means for supplying an oxidizing gas to said chamber to portion toward an outlet of said chamber, sepoxidize the surfaces of said lumps, means for, arating means to receive the powder as it sifts rotating said chamber to cause said oxidized surthrough said outlets, and means for returning to faces to be abraded by attrition, and to cause the said feeding means, powder too coarse to pass powder so abraded to be further abraded by the through said separating means.

lead lumps as it travels over said imperforate DANIEL DOYEN. 

